The use of hard coat stucco has been employed as a building material since literally ancient days. For stucco and plaster applications, a lath or mesh substrate is typically applied to the surface of the wall or ceiling structure. This provides a base for mechanical holding or keying for the unhardened stucco or plaster. Metal lath is often used as the reinforcement when stucco or plaster is applied over open frame construction, sheathed frame construction, or a solid base having a surface that might otherwise provide an unsatisfactory bond for the stucco or plaster. Plastic and other kinds of lath have also been used. When applied over frame construction, one may often employ base coats of plaster with a total thickness of approximately ⅜ inch to approximately ¾ inch to produce a solid base for a decorative finish coat.
According to the International Conference of Building Officials Acceptance Criteria for Cementitious Exterior Wall Coatings, AC 11, effective Oct. 1, 2002, and evaluation report NER-676, issued Jul. 1, 2003, wire fabric lath should be a minimum of No. 20 gauge, inch (25.4 mm) (spacing) galvanized steel woven-wire fabric. The lath should be self-furred, or furred when applied over all substrates except unbacked polystyrene board. Metal lath has structural integrity, but if made of steel can corrode over time. The metal can also unfavorably react with the chemistry of the plaster or stucco. Hence, plastic or non-metal lath has gained popularity.
Stone veneer has also gained in popularity. Mounting of stone veneer using lath can present similar issues to that of plaster and stucco. A concern with the stone veneer, and even stucco, is that moisture can find its way behind the outer stone or stucco surface. This can present itself by way of hole penetrations in putting up the lath, and water condensing or otherwise migrating behind the lath.
Also, a matrix of randomly oriented plastic or other durable fibers which are relatively rigid, or which can be treated to be relatively rigid or organized into a matrix that is relatively rigid, has been employed as the lath. An example of the foregoing kind of material is sold under the name MORTAR NET, sold by Mortar Net, Inc. of Burns Harbor, Ind., and such as disclosed in U.S. Pat. No. Re. 36,676. Such a matrix lath has typically been on the order of around except ¼″ thick (in front-to-back width).
Mortar Net, Inc. has created a system to allow water which may have penetrated cracks in the stucco or between the mortar and veneer to drain out, and to prevent water from entering the structure. To that end, a layer that forms a water channel layer has been applied in combination with the lath. The water channel layer has typically been of material similar to that of the foregoing matrix lath, but of a smaller fibrous diameter entangled randomly-oriented plastic or other durable fiber, formed in a thinner width, such as 3/16″ or ¼″ WALLNET product, made or sold under that name by Mortar Net, Inc. from stock material made by the Fiber Bond Corporation. More details of the foregoing system and product can be gleaned from U.S. application Ser. No. 13/838,993, filed Mar. 22, 2013.